After reading some positive comments on the net I decided to buy a Nikon DK-21M Magnifying Eyepiece for my D40. Not that I felt the standard viewfinder wasn't good enough for my needs, but more likely to see how much better it can get... So I paid a visit to my local camera shop and got one for under USD 30.00, tax included. Attaching it to the camera was quite easy - just remove the rubber eyepiece cup that comes with the camera and slide the DK-21M in its place. The instructions that came with it were clear and easy to follow.

The DK-21M has a magnification of about 1.17, which increases the total magnification of the D40 from about 80% to about 93-94%. The difference is notable as soon as you look through the upgraded viewfinder - so much so that I actually experienced vignetting!! It looks like the opening of the DK-21M is smaller than the one of the actual viewfinder, so the corners and the sides get a little bit darker... I could read the viewfinder info at the bottom pretty well, but I had to look down a little for that. I don't wear glasses though... After mounting the DK-21M you might need to adjust the diopter.

So far I only tried the DK-21M around the house. I plan to give it a more thorough "evaluation" on my next weekend photo outing and will report back here. One thing is sure - because the DK-21M protrudes more from the camera than the original eyepiece cup, there is less chance to touch the LCD with my cheek while taking photos

I was able to test the magnifier some more during this weekend. It really enlarges the entire image - the dark areas surrounding the TTL image in the viewfinder are greatly reduced and even eliminated (on the sides) while maintaining the same brightness. The problem is that I could not see clearly both the left and the right sides at the same time - no matter how I positioned my eye at least one of the sides was vignetting... if looking straight both of them are darkish. I could see the top and the bottom of the TTL image clearly at the same time, but not the viewfinder info... When I positioned the eye to see the viewfinder info completely the top of the TTL image would become darkish... This vignetting effect is relatively thin, but it is there... Of course, the actual image taken with the camera is not affected.

So there you have it... on the D40 at least there are some drawbacks in using the DK-21M... Having said this, I got used to it in the last 2 days so I'm going to keep it on for now

Darrin

P.S. The DK-21M is not compatible with all Nikon DSLRs - check on the camera page at Nikon USA in the accessories tab to see which magnifier works with your camera.